The trees that grow along urban streets are called street trees. Some street trees are planted between the street and the sidewalk. Other street trees are planted in a strip of land called the median, which lies in between the lanes of traffic. Trees that grow in front yards are considered street trees if part of their canopy covers public areas, such as the sidewalk or the street. The scientists in this study wanted to know how much of the sidewalks and streets were covered by tree canopies in Topics: Active Forest Management, Pollution, Water, Canopy Cover, Ecosystem Services, Global Warming, Inventory, Shade.